staging: ks7010: declare private functions static

Private functions in ks_hostif.c can be declared static.

Fixes: 13a9930d ("staging: ks7010: add driver from Nanonote extra-repository")

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>